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掺Cr4+:YAG晶体被动调Q激光器的研究

Research on Passively Q-Switched Laser with Cr4+:YAG Crystal

【作者】 李诚

【导师】 李武军;

【作者基本信息】 西安工业大学 , 光学, 2012, 硕士

【摘要】 使用激光二极管(LD)泵浦的固体激光器,与传统的激光器相比可以实现高输出功率、高重复频率,窄脉宽的激光输出。这种激光器的优点是体积小、效率高、结构简单、价格低廉等,因此在工业、科研、军事、医学、等领域中有着广泛的应用前景。成为海内外学者研究的热点。本论文采用光纤耦合的LD作为泵浦源,Nd3+:YAG晶体作为激光器的工作物质,可饱和吸收体Cr4+:YAG作为被动Q开关,并对4d3+:YAG晶体进行端面泵浦,分析研究了被动调Q激光器的脉冲输出特性。主要做了以下几个方面的工作:1)回顾了LD泵浦的固体激光器发展历程,讨论了典型被动Q开关材料Cr4+:YAG晶体的特性以及调Q激光器的工作原理。2)运用高斯分布近似下的速率方程,对调Q激光器进行了理论分析。3)实现了LD泵浦Nd3+:YAG晶体被动调Q1064nm激光器的运转,测量了不同泵浦功率、输出镜透过率和腔长下的输出功率、重复率、脉冲宽度;同时对实验结果进行了理论分析,得到了一致的结果。4)考虑到热效应的影响,对Q开关晶体的位置进行了研究,得出了Q开关晶体在谐振腔内的最佳位置,在此基础下,也确定了泵浦源的最佳位置。

【Abstract】 Compared with other lasers, the output of the laser-diode (LD) pumped solid-state laser is special in the high peak power, the high pulse repetition rate and the narrow pulse width. This kind of laser has been widely applied in the fields such as industrial, scientific research, military and medical, due to its advantages such as compact size, high efficient, simplicity and inexpensive. It has become the research focus of scholars from home and abroad.In this dissertation, by taking the fiber-coupled laser-diode as the pump source, Nd3+:YAG crystal as the gain medium, and the Cr4+:YAG storable absorber as the passive Q-switch, as well as by using the end-pumped to Nd3+:YAG crystal, we have studied the performance of the output pulse in the passively Q-switched laser. The main points of this paper can be summarized as follows:1) The development process of the LD pumped solid-state laser are reviewed. The characteristics of Cr4+:YAG crystal and theoretical foundation of Q-switch are analysed.2) The properties of the Q-switched laser have been theoretically analyzed by using of the Coupling rate equations under Gaussian distribution approximation3) The LD-pumped passively Q-switched Nd3+:YAG 1064nm laser has been realized; the output power, pulse repetition rate and pulse width have been worked out, when they at different pumped powers, transmittances of output mirror and cavity lengths; and the experimental results have been theoretically analyzed to a consistent conclusion.4) By considering the thermal effect of the medium, the optimal position of the Cr4+:YAG crystal in the laser cavity have been obtained from the study, and on the basis of this conclusion, the optimal position of the pump source have been found.

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